Auto-focus and zoom module with vibrational actuator and position sensing method

ABSTRACT

Systems for positioning a functional element, such as an optical lens, include a housing, a primary guide pin coupled to the housing, a functional group that includes the functional element, and a vibrational actuator assembly. The functional group is movably coupled with the primary guide pin and includes a first friction surface and a second friction surface. The first and second friction surfaces are oriented relative to one another at one of an obtuse angle and a straight angle. The vibrational actuator assembly is substantially registered relative to the housing and includes a first drive element and a second drive element. The first drive element is configured to interact with the first friction surface and the second drive element is configured to interact with the second friction surface. The vibrational actuator assembly operates to translate the functional group. Some embodiments include position sensing elements configured to detect position(s) of the functional element(s), and control system(s) configured to operate the actuators based on feedback from the position sensing system(s).

RELATED APPLICATIONS

This patent application claims priority under 35 U.S.C. 119(e) of theco-pending U.S. Provisional Patent Application No. 60/844,781, filedSep. 15, 2006, entitled “ZOOM MODULE WITH PIEZO WAVE ACTUATOR USING ENDSTOP AND AF/ZOOM POSITION SENSING METHOD, ARRANGEMENT AND METHOD OFDIRECT ACTIVATION OF FRONT LENS (AF/ZOOM) AND REAR LENS (ZOOM)COMPARTMENTS THROUGH SPECIAL CONFIGURED PIEZO WAVE ACTUATOR”, which ishereby incorporated by reference.

FIELD OF THE INVENTION

The disclosure relates to camera optics, specifically an auto-focus andzoom module.

BACKGROUND

Recently, there have been numerous developments in digital cameratechnology. One such development is the further miniaturization ofoptical and mechanical parts to the millimeter and sub millimeterdimensions. The shrinkage in the moving parts of cameras has allowed theimplementation of modern digital camera and optical technology into abroader range of devices. These devices are also constantly beingdesigned and constructed into smaller and smaller form factorembodiments. For example, these days typical personal electronic devicessuch as cellular phones, personal digital assistants (PDAs), and wristand/or pocket watches include a miniature digital camera. Moreover,larger form factor devices are also packed with additional features. Forexample, a typical video camcorder often has an entire digital camerafor “still” photography built into the camcorder device along with themechanisms and circuitry for motion video recording.

Typically, however, modern digital camera implementations suffer from avariety of constraints. Some of these constraints include cost, size,features, and complexity. For instance, with a reduction in sizetypically comes an increase in cost, a reduction in features and/or anincrease in complexity.

SUMMARY OF THE DISCLOSURE

In some embodiments of the present invention, an optical modulecomprises a first optics group, a second optics group, and an imagesensor, wherein the first optics group and second optics group areconfigured to provide an image having a focus and a magnification to theimage sensor.

Some embodiments are systems for positioning a functional element, suchas an optical lens, include a housing, a primary guide pin coupled tothe housing and registered relative to the housing, a functional groupthat includes the functional element, and a vibrational actuatorassembly. The functional group is movably coupled with the primary guidepin and includes a first friction surface and a second friction surface.The first and second friction surfaces are oriented relative to oneanother at one of an obtuse angle and a straight angle. The vibrationalactuator assembly is coupled to the housing and substantially registeredrelative to the housing, and it includes a first drive element and asecond drive element. The first drive element is configured to interactwith the first friction surface and the second drive element isconfigured to interact with the second friction surface. The vibrationalactuator assembly operates to translate the functional group. Someembodiments include position sensing elements configured to detectposition(s) of the functional element(s), and control system(s)configured to operate the actuators based on feedback from the positionsensing system(s).

Some embodiments are methods of driving a functional group within asystem for positioning a functional element. For example, a methodincluding steps of coupling a first friction surface to the functionalgroup, coupling a second friction surface to the functional group at oneof an obtuse angle and a straight angel to the first friction surface,configuring a first drive element of a vibrational actuator assembly tointeract with the first friction surface, configuring a second driveelement of the vibrational actuator assembly to interact with the secondfriction surface, and operating the first drive element and the seconddrive element of the vibrational actuator assembly to translate theoptics housing.

Some embodiments are optical modules. For example, an optical modulecomprising a housing, a primary guide pin, an optics group slidablycoupled to the primary guide pin, an optics element rigidly coupled tothe optics group, a vibrational actuator assembly, a sensing target, andan image sensor. The primary guide pin is coupled to the housing andregistered relative to the housing. Preferably, the optics groupincludes a first friction surface and a second friction surface. Thefirst and second friction surfaces are arranged along an axis parallelwith the primary guide pin. The first friction surface is directed alongan axis perpendicular to the primary guide pin. The second surfacedirected along the axis perpendicular to the primary guide pin in adirection substantially opposite the first friction surface. The‘direction’ of a friction surface refers to a normal vector out of thesurface. The optics element is coupled to the optics group. Thevibrational actuator assembly is substantially registered relative tothe housing and includes a first drive element and a second driveelement. The first drive element is configured to interact with thefirst friction surface and the second drive element is configured tointeract with the second friction surface. The vibrational actuatorassembly operates to translate the optics group. The sensing target isconfigured to permit detection of translation of the optics group.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth in the appendedclaims. However, for purpose of explanation, several embodiments of theinvention are set forth in the following figures.

FIG. 1A is an isometric view from an optics-group side of an auto-focusand zoom module in accordance with some embodiments of the invention;one optics group is rendered transparently to permit illustration of anactuator interface.

FIG. 1B is an elevation from an optics-group side of an auto-focus andzoom module in accordance with some embodiments of the invention; oneoptics group is rendered transparently to permit illustration of anactuator interface.

FIG. 2 is an isometric view from an optics-group side of an auto-focusand zoom module in accordance with some embodiments of the invention; anactuator housing is rendered transparently to permit a clear view of theactuator elements.

FIG. 3A is an isometric view from an optics-group side of an auto-focusand zoom module in accordance with some embodiments of the invention; ahousing is rendered transparently to permit a clear view of the actuatorelements.

FIG. 3B is an elevation from an actuator side of internal parts of anauto-focus and zoom module in accordance with some embodiments of theinvention.

FIG. 3C is an elevation from an optics-group side of internal parts ofan auto-focus and zoom module in accordance with some embodiments of theinvention.

FIG. 4 is an isometric view from an actuator side of an auto-focus andzoom module in accordance with some embodiments of the invention.

FIG. 5 is an isometric detail view of position sensing elementsconsistent with some embodiments of the invention.

FIG. 6A is an isometric view from an actuator side of internal partsrelated to position referencing consistent with some embodiments of thepresent invention.

FIG. 6B is a plan view of internal parts related to position referencingconsistent with some embodiments of the present invention.

FIG. 7 is an isometric view from an actuator side of an auto-focus andzoom module in accordance with some embodiments of the invention.

FIG. 8 is an isometric sectional view of an auto-focus and zoom modulein accordance with some embodiments of the invention

FIG. 9 is an isometric sectional view of an auto-focus and zoom modulein accordance with some embodiments of the invention.

FIG. 10 is an isometric view from below of an auto-focus and zoom modulein accordance with some embodiments of the invention.

FIG. 11 is an isometric view from above of an auto-focus and zoom modulein accordance with some embodiments of the invention; a main housing isincluded.

FIG. 12 is an isometric view from above of an auto-focus and zoom modulein accordance with some embodiments of the invention; a main housing andactuator springs are included.

FIG. 13 is an isometric view from of an actuator assembly from anauto-focus and zoom module in accordance with some embodiments of theinvention.

FIG. 14 is a flowchart illustrating a method of positioning a functionalelement within a system consistent with some embodiments of the presentinvention.

FIG. 15A is a schematic representation of a distance sensor inaccordance with some embodiments of the invention.

FIG. 15B is a schematic representation of beam spreading that occursduring distance sensing in accordance with some embodiments of theinvention.

FIG. 15C is a schematic representation of beam spreading that occursduring distance sensing in accordance with some embodiments of theinvention.

FIG. 16A is a schematic illustration of a direct imaging solution fordistance sensing in schematic representation of beam spreading thatoccurs during distance sensing in accordance with some embodiments ofthe invention.

FIG. 16B is a schematic illustration of a lens-based imaging solutionfor distance sensing in accordance with some embodiments of theinvention.

FIG. 16C is a schematic illustration of a pinhole-based imaging solutionfor distance sensing in accordance with some embodiments of theinvention.

FIG. 17 is a detailed schematic of an active area of interface between asensing target and a sensor consistent with some embodiments of theinvention.

FIG. 18 is a schematic representation of a signal produced from asensing target consistent with some embodiments of the invention.

DETAILED DESCRIPTION

In the following description, numerous details and alternatives are setforth for purpose of explanation. However, one of ordinary skill in theart will realize that the invention can be practiced without the use ofthese specific details. In other instances, well-known structures anddevices are shown in block diagram form in order not to obscure thedescription of the invention with unnecessary detail.

Structural Overview

Embodiments of the present invention include a variety of types ofmodules that include functional groups, actuators for positioning thosefunctional groups, and sensors and other control hardware forcontrolling the positioning of the functional groups. Though multipleimplementations are consistent with the present invention, two broadtypes of embodiments are discussed herein. These types of embodimentshave much in common, but there are some key differences.

In the first type, the actuator hardware is mounted in an actuatorhousing, which is separate from, but coupled to, a main housing thatincludes the functional groups and associated alignment hardware. Thesecond type is built around an integrated chassis that includes mountingfeatures for both the actuator hardware and for the functional groupsand their associated alignment hardware.

An exemplary module 100 of the first type is shown in FIG. 1A. A lateralaspect of the module 100 is shown, including a rear optics group 400 anda front optics group (dashed lines). The rear optics group 400 isslidably coupled to a primary guide pin 2. The optics groups are alignedalong an axis parallel to that of the primary guide pin 2. The rearoptics group 400 is coupled with actuators, e.g. 620 and 622,constrained within the actuator housing 1. The actuator housingcomprises structural and electrical couplings configured to permitoperation of the actuators. In operation, the rear actuators drive therear optics group 400 along the axis of the primary guide pin 2 via thecoupling between the actuator assembly and the rear optics group 400.The coupling between the front optics group and the actuator assemblypermits a front actuator to achieve a similar purpose.

An exemplary module of the second type is shown in FIGS. 10 and 11. FIG.11 shows the main housing 100, which couples the guide pins 2 and 3. Thefront and rear optics group are slidably coupled to the primary guidepin 2. The optics groups are aligned along an axis parallel to that ofthe primary guide pin 2. The actuators, e.g. 720′ and 722′, areconstrained via coupling to the main housing 100, as illustrated in FIG.11. The coupling to the main housing 100 comprises structural andelectrical couplings configured to permit operation of the actuators. Inoperation, the rear actuators drive the rear optics group along the axisof the primary guide pin 2 via the coupling between the actuatorassembly and the rear optics group. The coupling between the frontoptics group and the actuator assembly permits a front actuator toachieve a similar purpose.

Image Sensor

As shown in FIG. 3A, the image sensor 5 defines a plane. In the figures,this plane is perpendicular to the axes of the guide pins 2 and 3.Typically, a module is configured to provide an image to the imagesensor 5 along an image vector parallel to these axes. The image sensorplane is also illustrated in FIG. 10. In each of the embodimentsillustrated, an image vector delivered by the optics groups issubstantially perpendicular to the image sensor plane.

Guide Pins

In each of the illustrated embodiments, parallel guide pins function asconstraints along which the functional groups of the module arepositioned. Some embodiments include a pair of guide pins, while someembodiments employ a different number of guide pins. Regardless of theirnumber, the guide pins are typically mounted along a linear axis of themodule to permit the optical groups to move relative to the imagesensor.

For example, some embodiments of the first type include a guide pinarrangement as shown in FIGS. 2 and 3A. In the illustrated embodiment ofFIG. 3A, the optics groups 400 and 500 are slidably coupled to the guidepins 2 and 3. The optics group 400 is coupled to the primary guide pin 2via the primary rear guide sleeve 410 (FIG. 1A), and to the secondaryguide pin 3 via the rear guide slot 480. Similarly, the optics group 500is coupled to the primary guide pin 2 via the primary front guide sleeve510 (FIG. 2), and to the secondary guide pin 3 via the front guide slot580. In the module shown, the primary guide pin 2 and the secondaryguide pin 3 are aligned so that their axes are substantially parallel toeach other. The couplings between the optics group 400 and 500 and theguide pins 2 and 3 permit the rear barrel 430 and the front barrel 530to move along an axis parallel to that of the guide pins 2 and 3relative to the image sensor 5. Typically, the guide pins 2 and 3 arecoupled to a main housing (not shown) and an end guide plate (notshown). Preferably, the guide pins are coupled on opposite sides of theimage vector of the image sensor 5. However, one skilled in the art willrecognize that other configurations are possible.

Some embodiments of the second type include a guide pin arrangement asshown in FIGS. 7 and 11. In the illustrated embodiment of FIG. 7, theoptics groups are slidably coupled to the guide pins 2 and 3. The rearoptics group is coupled to the primary guide pin 2 via the primary rearguide sleeve 410′, and to the secondary guide pin 3 via the rear guideslot 480′ (FIG. 10). Similarly, the front optics group is coupled to theprimary guide pin 2 via the primary front guide sleeve 510′, and to thesecondary guide pin 3 via the front guide slot 580′ (FIG. 8). In themodule shown, the primary guide pin 2 and the secondary guide pin 3 arealigned so that their axes are substantially parallel to each other. Thecouplings between the front and rear optics groups and the guide pins 2and 3 permit the rear barrel 430′ and the front barrel 530′ to movealong an axis parallel to that of the guide pins 2 and 3 relative to theimage sensor. Typically, the guide pins 2 and 3 are coupled to a mainhousing 100 (FIG. 11) and an end guide plate 40 (FIG. 7). Preferably,the guide pins are coupled on opposite sides of the image vector of theimage sensor. However, one skilled in the art will recognize that otherconfigurations are possible.

In some embodiments, the range of motion provided to the rear barrel bythe guide pins is approximately 7 millimeters. In some embodiments, therange of motion provided to the front barrel by the guide pins isapproximately 2 millimeters. Due to this range of motion, however, theguide pins of some embodiments affect the form factor of the module.Hence, some embodiments further include means for modifying and/orconcealing the form factor of the module.

Prism Feature

For instance, some embodiments additionally include a prism feature (notshown). This feature allows the auto-focus and zoom module to be deposedand/or mounted in a variety of orientations. For instance, the dimensionavailable to a particular implementation along the initial direction ofan image vector is often limited such that the module is preferablydeposed lengthwise in the vertical plane of an enclosure. Thisorientation allows the range of motion of the front and rear barrelsalong the guide pins, as described above, to be implemented in a devicehaving a small width and/or depth form factor. For example, in a mobilephone implementation where a user will want to aim a camera at a desiredimage using the display as a viewfinder, the image vector isadvantageously perpendicular to the display for usability purposes.However, the dimension of the device perpendicular to the display isoften the thinnest dimension of a mobile phone.

In the relevant embodiments, a prism feature is mounted adjacent to thefront barrel. The prism redirects the light from an image at an anglewith respect to the front barrel. As described above, the front barreltypically houses a front lens group. The front lens group contains oneor more front optical elements. Hence inclusion of a prism allows amodule to be deposed in a variety of orientations within a device thatis typically held at an angle with respect to the subject being viewedand/or photographed.

Actuators

In the various embodiments, actuators are included and constrainedrelative to the main housing of the module. As mentioned, in someembodiments, the actuators are housed within an actuator housingseparate from, but coupled to, the main housing. In other embodiments,the actuators are coupled to the main housing.

An embodiment of the first type is shown in FIG. 2. The optics groups400 and 500 are coupled to a vibrational actuator assembly. Thevibrational actuator assembly (in general 10, 710-790, and 610-690 ofFIG. 2) actuates and controls translation of an optics group viainteraction between friction surfaces of the optics group and driveelements of the actuators. The actuators 620, 622, 720, and 722 arecoupled to the actuator housing (dashed line) and maintained in asubstantially stationary position relative to the main housing. This,combined with the freedom of the optics groups to move along the guidepins relative to the main housing, permits the actuators to move theoptics groups relative to the main housing.

An embodiment of the second type is shown in FIG. 10. The front and rearoptics groups are coupled to a vibrational actuator assembly. Thevibrational actuator assembly (in general 10′, 710′-722′, and 610′-622′of FIG. 10, not including springs) actuates and controls translation ofan optics group via interaction between friction surfaces of the opticsgroup and drive elements of the actuators. As shown in FIG. 11,actuators 620′, 622′, 720′, and 722′ are coupled to the main housing 100and maintained in a substantially stationary position relative to themain housing 100. This, combined with the freedom of the optics groupsto move along the guide pins relative to the main housing, permits theactuators to move the optics groups relative to the main housing.

Housing

In embodiments of the present invention, a main housing performs avariety of functions. It mechanically supports and registers the guidepins, image sensor, and prism (if present) relative to each other. Itprovides a support structure for electronic communications elements,e.g. flexible printed circuit boards that permit communication betweencontrol circuitry, actuators, and sensors. It provides light insulation.It preferably provides some measure of shock damage prevention.

The main housing also provides for mechanical coupling and support ofthe actuator assembly. In the first type of embodiment, discussed above,this includes mechanically registering with and supporting a separateactuator housing that comprises actuators, communications elements andconstraining elements. For example, the actuator housing 1 shown in FIG.1A is constrained relative to a main housing (not shown) and thusstationary relative to the guide pins during operation. The actuatorhousing 1 is also shown in FIG. 13.

In the second type of embodiment, a main housing provides for mechanicalcoupling and support of the actuator assembly through specializedfeatures for direct interface with an actuator assembly. For example, asshown in FIG. 12, the main housing 100 includes the interface features112, 114, 122, 124, 132, and 134 that constrain the actuator assembly,maintaining it substantially stationary relative to the guide pinsduring operation.

Lens System

The general features of the lens systems provided in the embodiments ofthe present invention are consistent across the various types ofembodiments. Certain aspects of the portions of these systems thatinterface with the guide pins and with the actuators do vary, asdiscussed in detail below.

Some general features of a rear optics group are illustrated in FIGS. 1Aand 3A. The rear optics group 400 includes the rear barrel 430, the rearguide sleeve 410, and the rear guide slot 480. The rear barrel typicallyhouses one or more lenses or other optical elements. The rear barrel 430is a substantially cylindrical body with a central axis. The lenses ofthe rear barrel (not shown) are configured to direct light along thecentral axis of the rear barrel 430. The rear guide sleeve 410 is anelongated, substantially cylindrical body coupled to the rear barrel 430so that the central axis of the rear barrel 430 and an axis of the rearguide sleeve 410 are substantially parallel. The rear guide slot 480 isa slotted feature configured to interface with a cylinder.

Some general features of a front optics group are illustrated in FIGS. 2and 3A. The front optics group 500 includes the front barrel 530, thefront guide sleeve 510, and the front guide slot 580. The front barreltypically houses a front lens. The front barrel 530 is a substantiallycylindrical body with a central axis. A front lens (not shown) ispreferably configured to direct light along the central axis of thefront barrel 530. The front guide sleeve 510 is an elongated,substantially cylindrical body coupled to the front barrel 530 so thatthe central axis of the front barrel 530 and an axis of the front guildsleeve 510 are substantially parallel. The front guide slot 580 is aslotted feature configured to interface with a cylinder.

Constrained by Guide Pins

Referring now to FIG. 2, the front optics group 500 includes the frontguide sleeve 510, which couples with the primary guide pin 2 (FIG. 3A).As illustrated, the front guide sleeve 510 is substantially elongatedrelative to the front barrel 530. Further, the front guide sleeve 510 isrigidly connected to the front barrel 530. This configuration preventsthe front optics group 500 from rotating around an axis perpendicular tothe axis of the primary guide pin 2, but permits rotation around theaxis of the primary guide pin 2. Referring now to FIG. 1A, the rearoptics group 400 includes the rear guide sleeve 410, which also coupleswith the primary guide pin 2. As illustrated, the rear guide sleeve 410is substantially elongated relative to the rear barrel 430. Further, therear guide sleeve 410 is rigidly connected to the rear barrel 430. Thisconfiguration prevents the rear optics group 400 from rotating around anaxis perpendicular to the primary guide pin 2, but permits rotationaround the axis of the guide pin.

Referring now to FIG. 3A, the front optics group 500 also includes thefront guide slot 580, configured to couple with the secondary guide pin3. The coupling between the guide slot 580 and the secondary guide pin 3prevents the front optics group 500 from rotating around the axis of theprimary guide pin 2. The coupling between the front optics group 500 andguide pins 2 and 3 permits the front optics group 500 to translate alongthe axis defined by the two guide pins, but not to move in either of theaxes orthogonal to that axis.

The rear optics group 400 includes the rear guide slot 480, configuredto couple with the secondary guide pin 3. The coupling between the guideslot 480 and the secondary guide pin 3 prevents the rear optics group400 from rotating around the axis of the primary guide pin 2. Thecoupling between the rear optics group 400 and guide pins 2 and 3permits the rear optics group 400 to translate along the axis defined bythe two guide pins, but not to move in either of the axes orthogonal tothat axis.

PRISM/Image Sensor

Driven Via Actuators

In the various embodiments of the present invention the functional, e.g.optics, groups include friction surfaces. In some embodiments thesefriction surfaces are integrally formed with structural portions of thegroup. In other embodiments, the friction surfaces are portions ofseparate friction plates that are coupled to structural portions of thegroup.

The friction surfaces of each optical group are configured relative toone another to permit control of movement along the axes of the guidepins via application of frictional forces to the surfaces. Preferably,the friction surfaces, the optical lens, and the guide pin areconfigured and oriented relative to one another to reduce orsubstantially eliminate undesired forces in the directions perpendicularto the axes of the guide pins, and to produce smooth movement of theoptical lens. Further, the friction surfaces and the guide sleeves arepreferably oriented such that the long axes of the friction surfaces areconstrained parallel to the axes of the guide pins.

For example, in FIG. 4 the long axes of the first and second rearfriction surfaces 442 and 444 are parallel to both the primary guide pin2 and the secondary guide pin 3, as shown in FIGS. 4 and 5. Thisalignment is maintained via the coupling between the friction surfacesand the guide sleeves. In FIG. 10, the long axes of the first and secondfront friction surfaces 542′ and 544′ are parallel to both the primaryguide pin and the secondary guide pin 3, and to the front guide sleeve510′.

Furthermore, friction plate mounting surfaces can be integrally formedwith guide sleeves portions of the optics groups, or mounted to abracket that is in turn mounted to the guide sleeve. Otherconfigurations are possible.

In the illustrated embodiments, the embodiments that include an actuatorhousing are amenable primarily to integrated friction plate mounts. Forexample, FIG. 4 illustrates a rear guide sleeve 410 including, twointegrated friction plate mounting surfaces, which are coupled withfriction plates forming the friction surfaces 442 and 444 as shown.Similarly, the front guide sleeve 510 includes integrally formedfriction plate mounting surfaces that mate to friction plates to formthe friction surfaces 542 and 544. As shown in FIG. 8, the thickness ofthe mounting structure 540 is greater than that of the primary guide pin2, permitting a highly degree of integral formation if desired.

In contrast, the embodiments that include an actuator assembly mountedto the main housing are more amenable to construction via coupling aseparate mounting surface to a guide sleeve. However, integrally formedapproaches are preferred. Referring to FIG. 7, a rear guide sleeve 410′includes two integrated friction plate mounting surfaces, which arerelatively close together compared with the embodiments of FIGS. 4 and8. The friction plate mounting surfaces are coupled with friction platesforming the friction surfaces 442′ and 444′ as shown. Similarly, thefront guide sleeve 510 includes integrally formed friction platemounting surfaces that mate to friction plates to form the frictionsurfaces 542′ and 544′. As shown in FIG. 9, the thickness of themounting structure 440′ is less than that of the primary guide pin 2,permitting a highly degree of integral formation if desired, but alsolending itself to construction via multiple components.

Drive Mechanism

The drive mechanism of the embodiments of the present inventioncomprises frictional surfaces mounted on optics groups, actuatorassemblies constrained in substantially stationary locations relative tothe main housing of an optical module, and drive elements configured totransmit force from the actuator assembly to the frictional surface.

Friction Surfaces on Functional Modules

The drive mechanism of the embodiments of the present invention relieson frictional surfaces on the functional modules being positioned. Inthe illustrated embodiments, optical modules are positioned viainteractions between actuators and frictional surfaces of frictionalplates coupled to the modules.

A goal of the present invention is to provide increased stability duringactuation by canceling any undesired forces generated by the interfaceof actuators with the friction surfaces. The configuration of the firstand second friction plates of an optical group relative to one anothercontributes to the reduction of forcing perpendicular to the guide pins.

For example, as illustrated in FIG. 5, the first rear friction surface442′ is configured on an opposite face of the friction plate mountingbracket 440′ from the second rear friction surface 444′. In anotherexample, FIG. 4 illustrates the friction plates 442 and 444 configuredon opposite sides of a mounting bracket integrally formed with the guidesleeve 410. Similarly, the FIG. 5 shows the first front friction plate542 configured on an opposite face of the friction plate mountingbracket 540 from the second front friction plate 544. FIG. 4 illustratesthe front friction surface 542 and 544 configured on opposite sides of amounting bracket integrally formed with the guide sleeve 510.

In both figures, each illustrating a different type of embodiment, eachgroup has two friction surfaces configured on opposite faces of aparallelepiped. This configuration represents one class of embodimentswhere the friction surfaces of a group are directed in oppositedirections of an axes perpendicular to the primary guide pin 2. Here the‘direction’ of a friction surface refers to the direction of its normalvector. Similarly, the ‘direction’ of a friction plate refers to thenormal vector of its friction surface that is exposed for interface withan actuator.

The opposed configuration of the friction surfaces in FIGS. 4 and 7 isbut one exemplary embodiment of the present invention's approach tofriction surfaces. In some embodiments, such as those illustrated,orienting the friction surfaces in opposite directions relative to oneanother at a straight angle reduces the side forces. Thus, with properoperation of the actuator, substantially all forces generated by on thefirst friction surface along vectors perpendicular to the guide pins canbe canceled by opposite forces generated by at the second frictionsurface. For example, control of the actuator can result insubstantially zero force being applied to the functional group alongvectors rotational around the axis of the primary guide pin.

In other embodiments, the friction surfaces are oriented relative to oneanother at an obtuse angle. In these embodiments, the some componentforces can be generated along an axis perpendicular to the guide pins 2and 3. Preferably these forces are aligned along a direction from theprimary guide pin 2 to the secondary guide pin 3 to reduce their effecton the reliability of the system. However, this configuration doesproduce some side forces on the guide pin and requires that the pinshave more rigidity. For at least this reason, these configurations arenot preferred.

In addition, the positioning of the friction surfaces relative to theprimary guide pin determines in part the level of side forcinggenerated. The center of mass of the optics modules lies between theguide pins 2 and 3. The friction surfaces, 442, 444, 542, and 544 in thefirst type of embodiment as shown in FIG. 4 as well as 442′, 444′, 542′,and 544′ in the second type of embodiment as shown in FIG. 7, lieoff-center to permit full range of motion of the optics groups. Thus,driving the optics modules at the friction surfaces tends to introduce atorque. However, configuring the groups so that the long axes of thefriction plates (and surfaces) are aligned or nearly aligned with theprimary guide pin 2 reduces the amount of torque on the guide pins.

For example, as illustrated in FIG. 1A, the first front friction surface542, the second front friction surface 544, and the primary guide pin 2are configured so that their long axes are aligned. The optics group isconfigured so that a single plane is substantially tangent to an edge ofeach of the friction plates and to a surface of the primary guide pin 2.This relative positioning of the guide pin 2 relative to the frictionsurfaces 542 and 544 is most clearly illustrated in FIG. 8. Thissingle-plane tangency is exhibited primarily in embodiments of the firsttype, e.g. those shown in FIGS. 1B, 2, and 3A-3C.

In some of these embodiments, a virtual line drawn between a point ofthe first friction surface, a point of the second friction surface, anda point of the primary guide pin is a straight line for at least onepoint from each at all times. This holds for both the front optics group500 and the rear optics group 400. For example, in FIG. 1A some portionof the first rear friction plate 442, the second rear friction plate444, and the primary guide pin 2 are coplanar. A similar configurationcan be seen in FIGS. 2 and 3A, though the pertinent portions of thesefigures are not all labeled.

FIG. 4 illustrates another version of this type of embodiment. Asillustrated, the first front friction surface 542 and the second frontfriction surface 544 along with the integrated mounting bracket of thefront guide sleeve 510 form a parallelepiped that has two opposingfriction surfaces. Also, the first rear friction surface 442 and thesecond rear friction surface 444 along with the integrated mountingbracket of the rear guide sleeve 410 form a parallelepiped that has twoopposing friction surfaces. In both the front guide sleeve 510 and therear guide sleeve 410, the parallelepiped formed intersects the primaryguide pin 2 when the group is mounted. In this configuration, forcertain sets of points with one point from each of the first rearfriction surface 442, the second rear friction surface 444, and theprimary guide pin 2, the set of points are coplanar. However, the longaxes of the guide pin 2 and the first rear friction surface 442 andsecond rear friction surface 444 are not coplanar. Similarly, and asshown in FIG. 5, certain sets of points with one point from each of thefirst front friction plate 542, the second front friction surface 544,and the primary guide pin 2, are coplanar. However, the long axes of theguide pin 2 and the first 542 and second 544 front friction surface arenot coplanar. Instead, a line drawn between the various axes forms atriangle. In preferred versions of these embodiments the triangle has aminimum area possible for a given spacing between the first and secondfriction surfaces.

In other embodiments, the primary guide pin and the friction surfacesare aligned differently. For example, in some embodiments, no virtualline drawn between any point of the first friction surface, the secondfriction surface, and the primary guide pin forms a straight line, butthe virtual line does form a triangle. FIG. 9 illustrates such aconfiguration. The first rear friction surface 442′ and the second rearfriction surface 444′ are configured on opposite sides of the mountingbracket 440, forming a parallelepiped with opposing friction surfaces.The parallelepiped and the primary guide pin 2 do not intersect. Thus,for no set of points with one point from each of the first rear frictionsurface 442′, the second rear friction surface 444′, and the primaryguide pin 2, is the set of points coplanar. However, there are sets ofpoints for which a line between such points forms a triangle. As shownin FIG. 7, the first front friction surface 542′, second front frictionsurface 544, and primary guide pin 2 are similarly related. In preferredversions of these embodiments the triangle has a minimum area possiblefor a given spacing between the first and second friction surfaces.

Drive Elements Coupled to the Friction Surfaces

The actuator assemblies mentioned above include drive elementsconfigured to interact with the friction surfaces of the functionalgroups. For example, as shown in FIG. 4, the actuator assembly isconfigured such that a first front drive element 710 interacts with afirst friction surface 542. Further a second front drive element 712interacts with the second friction surface 544. In addition, a firstrear drive element 610 interacts with a first rear friction surface 442and a second rear drive element 612 interacts with a second rearfriction surface 444. The remainder of the vibrational actuator assemblyis configured to effect and control movement of the drive elements toapply frictional forces to the friction surfaces of the front 500 andrear 400 optics groups.

As shown in FIG. 10 the actuator assembly is configured such that afirst front drive element 710′ interacts with a first front frictionsurface 542′. Further a second front drive element 712 interacts with asecond front friction surface 544′. In addition, a first rear driveelement 610′ interacts with a first rear friction surface 442′ and asecond rear drive element 612′ interacts with a second rear frictionsurface 444′. The remainder of the vibrational actuator assembly isconfigured to effect and control movement of the drive elements to applyfrictional forces to the friction surfaces of the front and rear opticsgroups.

The first and second friction surfaces of each functional, e.g. optical,group are coupled to the functional group as set forth above. Further,the first and second friction surfaces are configured relative to oneanother to permit the control of movement of the group along the guidepin axes via application of the friction surface. Thus, theconfiguration of the drive elements to apply frictional forces to thefriction surfaces permits the actuator to move, and to control movementof, the front optics group and the rear optics group. The type ofmovement over which the vibrational actuator preferably exercisesdynamic control is translation along the axes of the primary guide pin 2and the secondary guide pin 3. However, as mentioned earlier, theactuator can be configured to apply substantially zero rotational forcearound the primary axis of the primary guide pin 2.

The drive elements 710, 712, 610, and 612 as well as 710′, 712′, 610′,and 612′ are preferably hollow cylindrical bodies, configured to contacttheir respective friction surfaces along a tangent portion of an outercylindrical surface. Preferably the drive elements are constructed fromhigh friction ceramic materials capable of bonding with thepiezoelectric (vibrational) actuators. In some embodiments, the driveelements are integrally formed with the piezoelectric actuators.Preferably, the drive elements are constructed similarly to the drivepads disclosed and discussed in U.S. patent application Ser. No.10/173,766 of Johansson, filed Jun. 19, 2002 and entitled“Near-resonance electromechanical motor”, and in U.S. patent applicationSer. No. 10/737,791 of Mattsson, filed Dec. 18, 2003 and entitled“Electromechanical motor and method of assembling therefore.”

Vibrational Actuators Coupled to the Housing

An actuator assembly includes piezoelectric elements coupled to thedrive elements. Referring now to FIG. 4, the first rear drive element610 is coupled to the first rear piezoelectric element 620. The secondrear drive element 612 is coupled to the second rear piezoelectricelement 622. The first front drive element 710 is coupled to the firstfront piezoelectric element 720. The second front drive element 712 iscoupled to the second front piezoelectric element 722. Preferably, eachof the piezoelectric elements 620, 622, 720, and 722 is in the form of aparallelepiped. Preferably, the piezoelectric elements are constructedfrom piezoelectric materials, such as certain ceramics. In someembodiments, non-piezoelectric elements that are electrically actuatedto vibrate are used.

Similarly, in FIG. 10, the first rear drive element 610′ is coupled tothe first rear piezoelectric element 620′. The second rear drive element612′ is coupled to the second rear piezoelectric element 622′. The firstfront drive element 710′ is coupled to the first front piezoelectricelement 720′. The second front drive element 712′ is coupled to thesecond front piezoelectric element 722′. Preferably, each of thepiezoelectric elements 620′, 622′, 720′, and 722′ is in the form of aparallelepiped. Preferably, the piezoelectric elements are constructedfrom piezoelectric materials, such as certain ceramics. In someembodiments, non-piezoelectric elements that are electrically actuatedto vibrate are used.

Most preferably, the piezoelectric elements are constructed similarly tothe active portions of the drive elements disclosed and discussed inU.S. patent application Ser. No. 10/173,766 of Johansson, filed Jun. 19,2002 and entitled “Near-resonance electromechanical motor”. and in U.S.patent application Ser. No. 10/737,791 of Mattsson, filed Dec. 18, 2003and entitled “Electromechanical motor and method of assemblingtherefore.”

Each of the piezoelectric elements is coupled to a flexible actuatorboard and to a rigid mount. Preferably, dual-function couplings are usedto couple a piezoelectric element to both the mount and the actuatorboard. In a first type of embodiment, the actuator board is mounted toan actuator housing. For example, referring to FIG. 13, the first rearpiezoelectric element 620 is coupled to the actuator board 10 via thecouplings 632 and 634. In FIG. 4 this coupling is shown from the otherside, with the actuator housing 1 excluded. The couplings 632 and 634secure both the resilient actuator board 10 and the piezoelectricelement 620 to the actuator housing 1. Preferably, each coupling isflexible, permitting movement of the piezoelectric and accompanyingmovement of the resilient actuator board. In similar fashion, the secondrear piezoelectric element 622 is coupled to the actuator board 10 viathe couplings 636 and 638. The couplings 636 and 638 secure both theresilient actuator board 10 and the piezoelectric element 622 to theactuator housing 1. Similarly, FIG. 13 illustrates the second frontpiezoelectric element 722 coupled to the actuator board 10 via thecouplings 736 and 738. FIG. 4 illustrates the couplings 732 and 734,which similarly secure both the resilient actuator board 10 and thepiezoelectric element 720 to the actuator housing 1 (FIG. 13).

In a second type of embodiment the actuator board is mounted to the mainhousing. For example, as shown in FIG. 11, the first rear piezoelectricelement 620′ is coupled to the actuator board 10′ via the couplings 632′and 634′. The couplings 632′ and 634′ secure both the resilient actuatorboard 10′ and the piezoelectric element 620′ to the main housing 100. Asillustrated, special features of the main housing 100 are adapted toretain the actuator board 10′. Preferably, each coupling is flexible,permitting movement of the piezoelectric and accompanying movement ofthe resilient actuator board. In similar fashion, the second rearpiezoelectric element 622′ is coupled to the actuator board 10′ via thecouplings 636′ and 638′. The couplings 636′ and 638′ secure both theresilient actuator board 10′ and the piezoelectric element 622′ to themain housing 100. Similarly, the second front piezoelectric element 722′is coupled to the actuator board 10′ via the couplings 736′ and 738′.The couplings 732′ and 734′ similarly secure both the resilient actuatorboard 10′ and the piezoelectric element 720′ to the main housing 100.

Springs Provide Normal Force

Another factor in moderating interaction between the piezoelectricelements and the friction plates is the magnitude of normal forcebetween the drive elements and the friction plates. Preferably, a baselevel of normal force is generated via a clip spring configured to forcean opposing pair of piezoelectric elements toward one another, deformingthe actuator bracket, and increasing the normal force between thefriction plates and drive elements.

For example, the clip springs 690 and 790 are shown in FIG. 2. The clipspring 690 applies force to the first rear piezoelectric element 620 andthe second rear piezoelectric element 622 (not shown in FIG. 2),deforming the resilient actuator board 10 and forcing the piezoelectricelements 620 and 622 towards one another. Similarly, the clip spring 790applies force to the piezoelectric elements 720 and 722, forcing theelements towards one another and deforming the resilient actuator board10. The springs 690 and 790 urge the drive elements against the frictionplates, generating a normal force to ensure adequate frictional forcesbetween the elements.

Specifically, the spring 690 deforms the resilient actuator board 10 tourge the first rear piezoelectric element 620 and the second rearpiezoelectric element 622 towards one another, thus urging the firstrear drive element 410 against the first rear friction plate 442 and thesecond rear drive element 612 against the second rear friction plate444. The friction plates are constrained by their actuator housing toform a substantially rigid parallelepiped. The spring 690 simultaneouslyapplies force to the piezoelectric elements on either side of theparallelepiped, forcing them toward it and forcing the drive elementsagainst its friction surfaces.

The clip springs 690′ and 790′ are shown in FIG. 12. The clip spring690′ applies force to the first rear piezoelectric element 620′ and thesecond rear piezoelectric element 622′ (both shown in FIG. 11),deforming the resilient actuator board 10′ and forcing the piezoelectricelements 620′ and 622′ towards one another. Similarly, the clip spring790′ applies force to the piezoelectric elements 720′ and 722′, forcingthe elements towards one another and deforming the resilient actuatorboard 10′. The springs 690′ and 790′ urge the drive elements against thefriction plates, generating a normal force to ensure adequate frictionalforces between the elements.

Specifically, the spring 690′ deforms the resilient actuator board 10′to urge the first rear piezoelectric element 620′ and the second rearpiezoelectric element 622′ towards one another, thus urging the firstrear drive element 410′ against the first rear friction plate 442′ andthe second rear drive element 612′ against the second rear frictionplate 444′. The friction plates are constrained by their actuatorhousing to form a substantially rigid parallelepiped. The spring 690′simultaneously applies force to the piezoelectric elements on eitherside of the parallelepiped, forcing them toward it and forcing the driveelements against its friction surfaces.

Preferably the springs 690, 790, 690′ and 790′ are formed of a resilientmaterial such as metal. In the preferred embodiment, the spring 690 andthe spring 790 are identically configured and apply substantially thesame force to the sets of friction surfaces of their respectivefunctional groups. Similarly, the spring 690′ and the spring 790′ arepreferably identically configured and apply substantially the same forceto the sets of friction surfaces of their respective functional groups.However, the springs of 690 and 790 of the first type of embodiment arepreferably different than the springs 690′ and 790′ of the second typeof embodiment. One reason for this is the differing thickness of thefriction-surface-bearing parallelepiped between the first type andsecond type of embodiment. In some embodiments, springs are tuned toapply different forces to different functional groups.

The piezoelectric elements are preferably configurable to operate at aresonant frequency having at least two node points. In preferredembodiments, the couplings discussed above constrain each piezoelectricelement at its two node points. The piezoelectric elements arecontrolled via signals sent through the resilient actuator board 10 or10′, which preferably comprise resilient printed circuit board (PCB).

Actuator Control

Preferably, the module includes a control element (not shown), which isconfigured to receive data from the position sensor (discussed below)and to operate the vibrational actuators to position the functionalelement. In the first type of embodiments, the control element sendssignals through the actuator board 10 to control the piezoelectricelements 620, 622, 720, and 722. In the second type of embodiments, thecontrol element sends signals through the actuator board 10′ to controlthe piezoelectric elements 620′, 622′, 720′, and 722′. The piezoelectricelements are preferably controlled to operate at resonant frequenciesthat have node points at the locations of constraint.

For example, in the first type of embodiment, the first rearpiezoelectric 620 would operate at a resonant frequency that has nodepoints at the location of the couplings 632 and 634. Similarly, thesecond rear piezoelectric 622 would operate at a resonant frequency thathas node points at the location of the couplings 636 and 638. The frontpiezoelectric elements 720 and 722 would similarly relate to thecouplings 732, 734 and 736, 738, respectively.

Referring to FIG. 4, the resonant-driven piezoelectric elements 620,622, 720, and 722 engage and disengage the drive elements 610, 612, 710,and 712, with the friction plates 442, 444, 542, and 544, respectively.As discussed above, the configuration of the friction plates of a givenoptical group, e.g. the plates 442 and 444 of the rear optics group 400,relative to one another permits the actuator system to drive the groupalong the primary guide pin 2 substantially without any side forcing ofthe guide pin.

In the second type of embodiment, the first rear piezoelectric 620′would operate at a resonant frequency that has node points at thelocation of the couplings 632′ and 634′. Similarly, the second rearpiezoelectric 622′ would operate at a resonant frequency that has nodepoints at the location of the couplings 636′ and 638′. The frontpiezoelectric elements 720′ and 722′ would similarly relate to thecouplings 732′, 734′ and 736′, 738′, respectively.

Referring to FIG. 10, the resonant-driven piezoelectric elements 620′,622′, 720′, and 722′ engage and disengage the drive elements 610′, 612′,710′, and 712′, with the friction plates 442′, 444′, 542′, and 544′,respectively. As discussed above, the configuration of the frictionplates of a given optical group, e.g. the plates 442′ and 444′ of therear optics group, relative to one another permits the actuator systemto drive the group along the primary guide pin 2 substantially withoutany side forcing of the guide pin.

In both types of embodiment, the control element preferably drives theopposing piezoelectric elements that interact with a given group, e.g.the first rear piezoelectric element 620 and the second rearpiezoelectric element 622 that drive the rear optics group 400, in amanner selected to reduce or minimize side forcing. The frontpiezoelectric elements are also preferably controlled to minimizegeneration of forces perpendicular to the axes of the guide pins.

Position Sensing, Control and Referencing

In both types of embodiments, the present invention includes positionsensing, referencing and control components adapted to track movement ofthe optics groups and control the actuators to effect movement of theoptics groups via mechanisms discussed above. The details of theposition sensing and referencing operation are discussed below.

Actuator Mounting and Configuration Details

As mentioned above, the embodiments of the present invention include atleast two types differentiated by their approach to mounting an actuatorassembly to a module chassis. This section discusses these two types,their structure, and their function, in greater detail.

Actuator Housing—Main Housing

The first type of embodiment, shown generally in FIGS. 1-4, 8, and 13,includes both a main housing (not shown) and an actuator housing 1. Theactuator housing 1 is preferably rigidly coupled to the main housing,which also couples the guide pins 2 and 3, and the image sensor 6. Thus,the main housing registers the actuator housing 1, guide pins 2 and 3,and the image sensor 6 to one another.

Friction Surface—Optics Group

As described above, the optics groups 400 and 500 include guide sleeves410 and 510 and guide slots 480 and 580 configured to register thefunctional optics portion, e.g. 570 of FIG. 8, relative to the guidepins 2 and 3. The optics groups further include specialized mountingsurfaces configured to permit coupling of friction plates thereto andthus provide for optics groups with frictional surfaces thereon. Inother embodiments, the frictional surfaces are integrally formed withthe optics groups.

Specifically, as shown in FIG. 4, the optics groups each includefriction surfaces. Preferably, the friction surfaces are each embodiedin separate friction plates. Specifically, the rear optics group 400includes the first rear friction surface 442 and the second rearfriction surface 444. The front optics group 500 includes the firstfront friction surface 542 and the second front friction surface 544.The friction surfaces 442 and 444 belong to friction plates coupled withthe functional portion of the rear optics group, e.g. the rear barrel430 and its accompanying lens. Similarly, the friction surfaces 542 and544 belong to friction plates coupled with the functional portion of thefront optics group, e.g. the front barrel 530 and its accompanying lens570 (FIG. 8).

The friction surfaces are coupled to the functional groups through theguide sleeves, which constrain the surfaces relative to the guide pins.FIG. 8 illustrates the cross-sectional construction of theguide-sleeve-friction-plate interaction. As shown, the guide sleeve 510is integrally formed with the plate mounting bracket 540, which couplesthe plates, thus registering the friction surfaces 542 and 544 with thelens 570 through the preferably rigid coupling between the components ofthe front optics group 500.

Actuator Assembly—Optics Group

The actuator assembly and optics groups are coupled through driveelements. As shown in FIG. 8, the actuator assembly is configured suchthat a first front drive element 710 interacts with a first frontfriction surface 542. Further a second front drive element 712 interactswith the second front friction surface 544.

The remainder of the vibrational actuator assembly is configured toeffect and control movement of the drive elements to apply frictionalforces to the friction surfaces of the front 500 and rear 400 opticsgroups.

Preferably, as illustrated, the actuator assembly includes piezoelectricelements coupled to the drive elements. As shown in FIG. 1A, the firstrear drive element 610 is coupled to the first rear piezoelectricelement 620. Preferably, each of the piezoelectric elements is in theform of a parallelepiped. Preferably, the piezoelectric elements areconstructed from piezoelectric materials, such as certain ceramics.Preferably the drive elements are constructed of high-friction ceramics.In some embodiments, the drive elements and the piezoelectric elementsare integrally formed.

Most preferably, the piezoelectric elements are constructed similarly tothe active portions of the drive elements disclosed and discussed inU.S. patent application Ser. No. 10/173,766 of Johansson, filed Jun. 19,2002 and entitled “Near-resonance electromechanical motor”. and in U.S.patent application Ser. No. 10/737,791 of Mattsson, filed Dec. 18, 2003and entitled “Electromechanical motor and method of assemblingtherefore.”

Actuator—Actuator Housing

Each of the piezoelectric elements is coupled to a flexible actuatorboard 10 and to an actuator housing 1. Preferably, dual-functioncouplings are used to couple a piezoelectric element to both theactuator board 10 and to the actuator housing 1. Preferably, eachcoupling is flexible, permitting movement of the piezoelectric andaccompanying movement of the resilient actuator board. Preferably thecouplings are located at points on the piezoelectric elements that arenode points under preferred resonant operating conditions.

Referring to FIG. 13, the first rear piezoelectric element 620 iscoupled to the actuator board 10 via the couplings 632 and 634. Thecouplings 632 and 634 secure both the resilient actuator board 10 andthe piezoelectric element 620 to the actuator housing 1.

In similar fashion, the second rear piezoelectric element 622 is coupledto the actuator board 10 via the couplings 636 and 638. The couplings636 and 638 secure both the resilient actuator board 10 and thepiezoelectric element 622 to the actuator housing 1. Similarly, thesecond front piezoelectric element 722 coupled to the actuator board 10and actuator housing 1 via the couplings 736 and 738.

Actuator Housing—Main Housing

Still referring to FIG. 13, the actuator housing 1 includes features forinterface with a main housing (not shown). Specifically, the actuatorhousing 1 includes the front interface latch recess 12, the rear latch16, the front reference aperture 14 and the rear reference aperture 18.

The entirety of the actuator housing 1 is preferably constructed of arigid material, thus registering the front interface latch recess 12,the rear latch 16, the front reference aperture 14 and the rearreference aperture 18 relative to one another. The main housing, inaddition to registering the guide pins 2 and 3, and the image sensor 6to one another, further registers the complement features of the frontinterface latch recess 12, the rear latch 16, the front referenceaperture 14 and the rear reference aperture 18. Thus, thru its rigidcoupling to the main housing, the actuator housing 1 is preferablyregistered to the optics groups coupled to the guide pins 2 and 3.

Multi-Function Main Housing Chassis

The second type of embodiment, shown generally in FIGS. 4-7, and 9-12,includes a multi-function main housing 100. The main housing 100 couplesthe guide pins 2 and 3, the image sensor 6, as well as the actuatorassembly. Thus, the main housing registers the actuator assembly, guidepins 2 and 3, and the image sensor 6 to one another.

Friction Surface—Optics Group

As described above, the optics groups include guide sleeves 410′ and510′ and guide slots 480′ and 580′ configured to register the functionaloptics portion, e.g. within the barrels 430′ and 530′ of FIG. 10,relative to the guide pins 2 and 3. The optics groups further includespecialized mounting surfaces configured to permit coupling of frictionplates thereto and thus provide for optics groups with frictionalsurfaces thereon. In other embodiments, the frictional surfaces areintegrally formed with the optics groups.

Specifically, as shown in FIG. 7, the optics groups each includefriction surfaces. Preferably, the friction surfaces are each embodiedin separate friction plates. Specifically, the rear optics groupincludes the first rear friction surface 442′ and the second rearfriction surface 444′. The front optics group includes the first frontfriction surface 542′ and the second front friction surface 544′. Thefriction surfaces 442′ and 444′ belong to friction plates coupled withthe functional portion of the rear optics group, e.g. the rear barrel430′ and its accompanying lens. Similarly, the friction surfaces 542′and 544′ belong to friction plates coupled with the functional portionof the front optics group, e.g. the front barrel 530′ and itsaccompanying lens.

The friction surfaces are coupled to the functional groups through theguide sleeves, which constrain the surfaces relative to the guide pins.FIG. 9 illustrates the cross-sectional construction of theguide-sleeve-friction-plate interaction. As shown, the guide sleeve 410′is integrally formed with the plate mounting bracket 440′, which couplesthe plates, thus registering the friction surfaces 442′ and 444′ withthe lens through the preferably rigid coupling between the components ofthe optics group.

Actuator Assembly—Optics Group

The actuator assembly and optics groups are coupled through driveelements. As shown in FIG. 10, the actuator assembly is configured suchthat a first front drive element 710′ interacts with a first frontfriction surface 542′. Further a second front drive element 712′interacts with the second front friction surface 544′.

The remainder of the vibrational actuator assembly is configured toeffect and control movement of the drive elements to apply frictionalforces to the friction surfaces of the front and rear optics groups.

Preferably, as illustrated, the actuator assembly includes piezoelectricelements coupled to the drive elements. As shown in FIG. 10, the firstrear drive element 610′ is coupled to the first rear piezoelectricelement 620′. Preferably, each of the piezoelectric elements is in theform of a parallelepiped. Preferably, the piezoelectric elements areconstructed from piezoelectric materials, such as certain ceramics.Preferably the drive elements are constructed of high-friction ceramics.In some embodiments, the drive elements and the piezoelectric elementsare integrally formed.

Most preferably, the piezoelectric elements are constructed similarly tothe active portions of the drive elements disclosed and discussed inU.S. patent application Ser. No. 10/173,766 of Johansson, filed Jun. 19,2002 and entitled “Near-resonance electromechanical motor”, and in U.S.patent application Ser. No. 10/737,791 of Mattsson, filed Dec. 18, 2003and entitled “Electromechanical motor and method of assemblingtherefore.”

Actuator—Main Housing

Each of the piezoelectric elements is coupled to a flexible actuatorboard 10′ and therethrough to the main housing 100. Preferably, flexiblecouplings are used to couple a piezoelectric element to the actuatorboard 10. Preferably, each coupling permits movement of thepiezoelectric and accompanying movement of the resilient actuator board10′. Preferably the couplings are located at points on the piezoelectricelements that are node points under preferred resonant operatingconditions.

Referring to FIG. 11, the first rear piezoelectric element 620′ iscoupled to the actuator board 10′ via the couplings 632′ and 634′. Theresilient actuator board 10′ is coupled to the housing 100 at theactuator board interface features 112, 114, 122, 124, 132, and 134.Referring to FIG. 10, the resilient actuator board 10′ includes aplurality of mounting features 11, 11 a, 12, 12 a, 13, and 13 aconfigured to interface with the actuator board interface features ofthe main housing 100.

Further, referring to FIG. 9, the resilient actuator board 10′ iscoupled along a top surface of the housing 100, and through a connector50 interfaces with a top branch 36 of the main printed circuit board 30(see FIG. 7).

The actuator assembly structural features 110, 120, and 130 host theactuator board interface features 112, 114, 122, 124, 132, and 134, andprovide a structural separation between the actuators, registering themrelative to the main housing 100. The couplings 632′ and 634′ secure theresilient actuator board 10′ to the piezoelectric elements, constrainingthe elements to positions permitted by the resilience of the actuatorboard and the couplings themselves.

In similar fashion, the second rear piezoelectric element 622′ iscoupled to the actuator board 10′ via the couplings 636′ and 638′.Similarly, the first and second front piezoelectric elements are coupledto the resilient actuator board and therethrough to the main housing viatheir respective couplings.

The entirety of the main housing 100 is preferably constructed of arigid material, thus registering actuator assembly structural features110, 120, and 130 and their respective interface features relative toone another. In addition, these features are registered to the guidepins 2 and 3, and the image sensor 6. Thus, this configuration registersthe actuator board relative 10′ to the optics groups. Though theresilience of the actuator board 10′ permits the actuators to beslightly displaced, it registers them to a substantially fixed location.

Position Sensing, Control and Referencing Components

In both types of embodiments, the present invention includes positionsensing, control and referencing features adapted to track movement ofthe optics groups and control the actuators to effect movement of theoptics groups via mechanisms discussed above. The illustratedembodiments of FIGS. 5-7 and 10 most clearly show the components andfeatures associated with these functions. However, consistent with thepresent invention, other embodiments and types of embodiments includethese features.

Sensing Target

Some embodiments of the present invention include sensing targets toprovide feedback on positioning. In some embodiments, a sensing targetis disposed on a lead screw. In some embodiments, a sensing target isdisposed on an optics group. Linear targets are consistent with thepresent invention. In addition, distance-measuring targets are alsoconsidered.

In some embodiments of the present invention a functional group, e.g.the rear optics group 400, includes a sensing target. In FIG. 10, alinear sensing target 490′ is included in a rear functional group,positioned adjacent to the guide sleeve 410′. The position sensingtarget 490′ is configured to engage with the position sensor 910. Theposition sensing target 490′ includes a plurality of features 495′ toaid in position sensing.

Linear targets are acceptable in relatively low precision positioningapplications. Further, linear targets are preferred in applicationswhere the target need move over a relatively large range. Here, thelinear target is employed in the rear optics group because the group isused for zoom purposes.

In some embodiments, a distance sensing target is included as part of anoptics group. FIG. 10 illustrates the sensing target 590′ configured aspart of the front optics group. Here, the target 590′ is constructed asan integral part of the optics group. However, in some embodiments, asensing target is modular, or merely coupled with an optics group. Thetarget 590′ is configured to engage with the position sensor 920 (FIG.7), which is preferably a direct distance sensor. The target 590comprises some reflecting surface. In some embodiments the target 590′includes a pattern or reflectivity gradient. Preferably a circularreflectivity gradient is used.

Sensors

The embodiments of the present invention include position sensorsadapted to sense a variety of targets. For example, linear targets areconsistent with the present invention. In addition, distance-measuringtargets are also considered.

In some embodiments of the present invention a functional group, e.g.the rear optics group 400, includes a sensing target. In FIG. 7, alinear sensing target included on the rear functional group is engagedwith a linear position sensor 910. The position sensor 910 is engaged todetect the movement of the sensing target, for example via changes inits reflectance due to surface features. Linear sensors are acceptablein relatively low precision positioning applications. Further, linearsensors are preferred in applications where the target need move over arelatively large range, as the sensor remains engaged along the fulllength of the linear target. The linear sensor is employed in the rearoptics group because the group is used for zoom purposes.

In some embodiments, a distance sensor is employed. FIG. 7 alsoillustrates the distance sensor 920, engaged with the distance target ofthe front optics group. Preferably the sensor 920 is a direct distancesensor configured to sense changes in reflectance as the target changesits distance from the sensor.

Sensors are preferably coupled to control systems via communicationscircuitry. In the illustrated embodiments, the position sensor 910 iscoupled via the front branch 32 to a main PCB 30. Similarly, theposition sensor 920 is coupled via the rear branch 34 of the main PCB30.

Further, the sensors are preferably coupled to the main housing 100 toregister them relative to the remainder of the module, and to supportthem structurally. The figures that include the main housing 100 do notshow the sensors, however, as they are preferably within the structureof the housing.

Control

The position sensors 910 and 920, as well as the actuator assembly, arecoupled through communications circuitry to a main PCB 30, which ispreferably coupled to a control system (not shown). As illustrated, inFIGS. 7 and 9, the front branch 32 couples the distance position sensor920, the rear branch 34 couples the linear position sensor 910, and thetop branch 36 couples the actuator assembly (through the actuator board10′ and the connector 50).

Preferably, the control system is configured to receive signals from theposition sensors and to control the actuators based on those signals andon other input. One other source of input is hard stop referencing asdescribed below. Further, the system preferably performs a variety ofprocessing and operational features as described below in the “PositionSensing” section.

Mechanical Hard Stop Latch

Preferably, embodiments of the present invention include featuresconfigured to permit referencing of an optics group via mechanical hardstop.

Referring now to FIGS. 6A and 6B, these include a snap-fit arrangementbetween the front optics group 500 and the pin alignment guide plate 40.In other embodiments, the main frame provides a hard stop. For example,in an end-stop position the back edge of the rear guide sleeve isstopped against the main housing of the module (not shown).

To provide mechanical stop capabilities, the snap-fit arrangementrequires specialized features on both the pin alignment guide plate 40and the front optics group. The front optics group includes thereference pocket 514, as shown in FIG. 6A. The reference pocket 514 isarranged along the axis of the primary guide pin 2, adjacent to theguide sleeve 510. The wall of the reference pocket 514 proximal to theguide sleeve 510 provides a mechanical hard stop reference for theextreme forward position (furthest from the image sensor) in the rangeof optics group. Similarly, the forward wall 512 of the reference pocket514 distal from the guide sleeve 510 provides a mechanical hard stopreference for the extreme near position (closest to the image sensor) inthe range of front optics group. The actual mechanical stop of the frontoptics group at the reference points is provided by the interfacebetween the reference pocket 514 and the mechanical stop element 20 ofthe pin alignment guide plate 40, as shown in FIG. 6B.

Referring now to FIG. 6B, the extreme forward position of the frontoptics group is shown. As illustrated the interface between themechanical stop element 20 and the reference pocket 514 is mechanicallypreventing the front optics group from moving further from the sensor.The latch portion 22 of the mechanical stop element 20 provides a hardstop at the other extreme position by interlacing with the forward wall512 of the reference pocket 514. As illustrated, the latch portion‘snaps’ in to the reference pocket 514 and its flat portion serves asthe reference stop.

Because both hard stop references are provided by the same part(mechanical stop element 20) this configuration can be used toaccomplish automated calibration of the position sensors as the distancebetween the two extreme positions is relatively well defined.

Position Sensing

Embodiments of the present invention include position-sensing elementsconfigured to provide feedback to an actuator control system. Theseelements permit the module to accurately position functional groups,e.g. optics, by using non-linear actuator motors.

Preferred embodiments of the present invention employ a sensing targetthat moves in concert with a functional group of the module, and asensor configured to detect and encode data representing movement of thesensing target. For example, some embodiments use reflection encoding ofa mobile sensing target that comprises regions of differing reflectance.Other embodiments use direct encoding of linear distances, in some casesjudged via reflection from a target that has a reflectance gradient. Anexemplary position sensing system comprises the position sensors 910 and920 and the position sensing targets 490 and 590 shown in FIG. 5 alongwith control and communications hardware.

Reflection Feature Encoding

In the exemplary reflection encoding system, a sensor includes anelement that emits radiation and an element that detects radiation. Atarget includes dark and light bands, for example. The dark bands tendto absorb a greater proportion of the emitted radiation than do thelight bands. The sensor detects the radiation reflected by the bands. Asthe target moves relative to the sensor, the absorption and reflectanceof the sensing target portion aligned with the sensor varies. The sensorencodes this variation. A variety of encoding algorithms and processesare consistent with the present invention. For example, a sensor couldsimply detect each transition between a dark and light band. In anotherexample, a sensor could simply encode the variation in intensity as atarget changes its distance from the sensor.

System Resolution

The resolution of a reflection encoding system is determined by severalfactors. The distance between the emitter/detector and the target, thebeam spread of the radiation used, and the native target resolution allplay important roles in determining a system's resolution. These threefactors do not act separately, rather they interact, and each must betuned relative to the others.

In a linear system, native target resolution is essentially a functionof feature size. The smaller the critical dimension—the dimensionparallel to sensor movement—of a target's features, the greater itsnative target resolution. For example the target 490 of FIG. 5 usesstripe pairs as features. The sensing system is configured to movestripes along their narrow dimension across a sensor's field of view.Thus a critical dimension of a stripe pair in the illustratedconfiguration is its width along the narrow dimension.

However, a position sensing system does not guarantee high resolutionsimply by using a high native target resolution. A suitable combinationof low beam spread radiation and tight emitter-target tolerances isrequired to achieve a maximal resolution permitted by a given featuresize. The beam spread and tolerance specifications are complementary: adecrease in beam spread combined with an appropriate increase intolerance can maintain a given resolution, and vice versa.

For a given feature size, there is a maximum radiation beam spread abovewhich the features are not resolvable via reflection encoding. FIG. 15Billustrates the maximum beam spread for a series of light sources (whitesquares on left hand side) emitting light towards a series of absorptiveand reflective bands (right hand side). The detail shown in FIG. 15Cillustrates a 20-micron wide light source paired with a target havingsimilarly-sized features. In this case, the maximum tolerable spread is10 microns.

Under set diffusion conditions, the maximum tolerable spread and desiredresolution determine a maximum spacing between a radiation source andthe target. This spacing, distance d in FIG. 15C, is proportional to therequired resolution, and inversely proportional to the tangent of anangle representing the diffusion of the radiation. For example, given atypical LED diffusion angle of 10 degrees, to achieve 10 micronresolution the distance d should be less than 56.7 microns. Thus, toachieve the native target resolution, a suitable combination of beamspread radiation and spacing should be employed.

Native Target Resolution

Some embodiments of the present invention employ position sensingsystems with beam spread and tolerance optimized to operate at nativetarget resolution. In reflection encoding, a variety of methods,strategies, and devices are available to achieve this goal.

FIG. 16A illustrates a direct imaging approach where a radiation emitter(white rectangle), e.g. an LED, produces radiation, which is supplied tothe target without additional processing. A portion of the radiationreflecting from the target is detected by a detector (hatchedrectangle). In this type of approach, the emitter must produce radiationwith a sufficiently low beam spread to resolve the target features.

Tolerances

One method of achieving native target resolution is closely spacing theemitter/detector and the scanning target. However, tightening tolerancesincreases the precision required in manufacturing both the target, andthe device as a whole. For these and other reasons, embodiments of thepresent invention preferably space the emitter/detector and scanningtarget at distances achievable within tolerances typical of massmanufacturing.

Active Area—Emitter/Detector Modification

Several combinations of features and methods can be employed to lessenthe spacing requirements tolerances or decrease problems caused bydiffusion of the radiation. In reflection encoding, a portion of thesensing target is excited by radiation and a detector receives a signalfrom the sensing target. The signal received represents thecharacteristics of an active area of the sensing target. Preferably, theactive area is sized and located to match critical feature dimensions ofthe sensing target. For example, FIG. 17 illustrates the active area ofa sensing target.

The size and location of the active area are determined bycharacteristics of both the emitter and the detector. In some cases, theradiation is conditioned to limit the portion of the sensing targetexcited by radiation. In some cases, the field of view of the detectoris cropped.

Some techniques involve radiation processing measures that permit theuse of higher resolution targets at manufacturable spacing than would bepossible using more diffusive radiation. FIG. 16B illustrates a systemin which a lens is used to collimate radiation from a detector.Collimating the radiation permits target-sensor spacing to increaserelative to direct imaging while maintaining ability to resolve a setfeature size. The maximum spacing and resolvable feature sizes aredetermined by the spreading of the radiation following collimation.

Some techniques involve elements configured to limit the field of viewof a sensor to a portion of its native field of view. FIG. 16Cillustrates a system in which a pinhole is used to prevent ‘bleed over’from an adjacent region from preventing detection of a transition. Inthis case, reflected radiation must pass through the centered pinholeplaced near to the target surface before reaching the detector. Thissystem can require higher intensity emitters, as relatively littleradiation is available through the pinhole.

Though certain embodiments of the present invention do employ activearea cropping strategies, such as radiation conditioning, the additionaldevices or features needed to carry out these strategies increases thecost and complexity of the manufactured module. Preferably, embodimentsof the present invention employ other means to achieve desiredresolutions.

Beyond Native Target Resolution

At certain thresholds, achieving high system resolution though use ofhigh native target resolution begins to necessitate radiationconditioning or tight spacing. As outlined above, these elementsincrease the complexity of a module and the precision required inmanufacturing. Therefore, for resolutions above these thresholds,embodiments of the present invention preferably employ a lower nativetarget resolution combined with at least one of a variety of strategiesfor achieving system resolution greater than native target resolution.

Active Area

The methods of defining an active area referred to above relate toconditioning radiation from an emitter, selecting a detector with anappropriate field of view, or modifying the field of view using anexternal device.

Preferably, the sensing target and detector are configured such that asingle feature dominates the field of view. For example, as illustratedin FIG. 17, an active area is sized to match the width of a stripe pair.Typically, the feature size of the target is chosen based on the fieldof view. However, the required resolution can also be a factor indetermining feature size.

Data Processing

Preferably, embodiments of the present invention process data from asensor to achieve resolutions higher than native target resolution. Avariety of processing techniques, methods and elements are employedwithin various embodiments of the invention, including threshold-basedsignal conversion and interpolation.

Preferably, embodiments of the present invention encode a portion of thesensing target within the active area into a voltage. The voltage variesdepending on the character of the portion of the sensing target withinthe active area at time of encoding.

Embodiments of the present invention preferably match the dimensions ofthe active area to the critical dimensions of the sensing targetfeatures in order to produce a smoothly varying signal. FIG. 17illustrates a preferred relationship between the active area and sensingtarget feature dimensions. The active area is sufficiently large alongthe direction of the critical dimensions so that it will notsequentially encounter regions with the same light/dark characteristics.In the illustrated embodiment, along the critical dimension the activearea is larger than one feature's width and smaller than twice thatwidth. This type of configuration substantially prevents ‘flat’ spotsfrom occurring within the analog signal produced.

Over time, as the sensing target moves through the active area, thesystem forms a signal representing the portions of the sensing regionthat have passed through the area. As shown in FIG. 18, a sensingtarget, part 1, and a varying signal, part 2, are correlated along atime axis t. The strength of the signal in part 2 at a given point intime is determined by the characteristics, e.g. the proportion of lightand dark stripe, within the active region at that time. As illustrated,the minima of the signal in part 2 correspond in time to the centralaxes of the dark stripes. Similarly, the maxima of the signal in part 2correspond in time to the central axes of the light stripes.

In some embodiments the signal is a continuous encoding of the voltage,in other embodiments the signal is a series of discrete samples taken ata particular frequency. In either case, the signal preferably containsmultiple samples related to each feature of the sensing target as itmoves across the sensor's field of view.

The encoding process produces a variable signal representing themovement of the sensing target. The minima and maxima of the signalrepresent movement of the sensing target at its native targetresolution. Preferably, this variable signal is an analog voltage. Insome embodiments, interpolation is used to construct higher resolutiondata between the minima and maxima of the variable signal. Preferablythe interpolation error occurs only within a given period of the nativetarget resolution and is reset with each minimum or maximum of thesignal. This limits the error introduced by interpolation to asubstantially fixed percentage of the native resolution.

A processing system receives a variable signal from the sensor andproduces corrected movement data at a resolution higher than nativetarget resolution. For example, in some embodiments, the analog voltagesignal is supplied to an analog to digital converter (ADC). The analogsignal, which was produced at a sampling rate that results in multiplesamples per feature, contains sufficient information to support ADCproduction of digital signal with a resolution greater than nativetarget resolution. In some embodiments, an ADC process using multiplethresholds is used to encode an analog signal to a higher-resolutiondigital signal.

The corrected movement data is then translated into position data thatrepresents the position of a functional group coupled to the sensingtarget. For example, in some embodiments digital data from the ADC issupplied to a controller where it is analyzed and translated intoposition data.

Preferably, embodiments include additional calibration of processingcircuitry. In the preferred embodiment, an initial calibration isaccomplished automatically during power on. For example, in an ADC-basedsystem, self-calibration during power-on preferably determines the inputrange needed for data. Embodiments that use self-calibration do notrequire initial calibration during manufacturing or storage of fixedcalibration parameters over their lifetime. In addition, the calibrationpreferably defines the initial position for each functional group. Insome embodiments, these initial positions are determined by a hardreference stop discussed elsewhere in greater detail. In someembodiments, the positions are determined via information embedded intothe sensing target. In some embodiments, position is referenced by theabsence of interaction between the sensor and sensing target.Specifically, referring to the mechanical hard stop references describedabove with reference to FIGS. 5, 6A, and 6B are preferably used asreferences as described above. In addition, the overall distance betweenreference stops can be used to recalibrate the position sensors.

However, some embodiments also include continuous calibration duringsensing to handle signals with noisy time-variance. A variety ofconfigurations produce signals with slight instabilities over time. Forexample, FIG. 18, part 3 illustrates a signal with an average magnitudethat ‘wobbles’. A variety of design and manufacturing decisions mayresult in such signals, for example physical wobbling of sensing targetsdue to manufactured tolerances. In some embodiments a calibrationconstant correlated to instabilities is used to counteract them anddynamically correct tie processing output. An exemplary calibrationconstant is the average magnitude over a trailing time or frequencyperiod.

In some embodiments, non-volatile memory elements are included in thecontrol or processing circuitry and used to provide additionalmanufacturing and calibration data. Preferably, this additional data isused to adjust for component variation and manufacturing tolerances.

Some embodiments that employ interpolation use additional hardwareand/or firmware (e.g. a clock for timing and for analysis). If theactuator is very non-linear, interpolation can introduce positioningerror. Preferably, embodiments of the present invention use ADCtechniques.

Direct Distance Encoding

In an exemplary distance detecting system, a sensor includes an elementthat emits radiation and an element that detects radiation. A targetincludes reflective portions, for example. An exemplary target couldsimply be a uniform reflective surface. However, to extend range orincrease uniformity of response, the use of targets with patterns,including three dimensional patterns, or gradients of reflectivity isconsidered. One example is a corner-cube reflector used to increasedirected reflectance of oblique radiation components. The sensor detectsthe radiation reflected by the target. As the target moves relative tothe sensor, the intensity of the radiation reflected from the sensingtarget increases or decreases accordingly. The sensor encodes thisvariation. A variety of encoding algorithms and processes are consistentwith the present invention. For example, a sensor could simply detectthe overall intensity. In another example, a sensor could simply encodethe change in intensity over time.

System Resolution

The resolution of a distance encoding system is determined by severalfactors. The strength of the emitter, the beam spread of the radiationused, and the presence of features on the target all play importantroles in determining a system's resolution. These factors do not actseparately, rather they interact, and each must be tuned relative to theothers.

In a distance system, native target resolution is essentially a functionof the features present on the target. For example, if the target has areflectivity gradient, the reflectance of the target yields higherdensity information than does a uniformly reflective target

However, a position sensing system does not guarantee high resolutionsimply by using a high native target resolution. A suitable combinationa sufficient signal-to-noise ratio, yielded by low beam spreadradiation, the target, and a precise sensor, and sufficient AD converterresolution is required to achieve a maximal resolution permitted by agiven target.

Active Area—Emitter/Detector Modification

Several combinations of features and methods can be employed to decreaseproblems caused by diffusion of the radiation. In distance encoding, thesensing target is excited by radiation and a detector receives a signalfrom the sensing target. The signal received represents thecharacteristics of an active area of the sensing target.

Preferably, the entire sensing target is excited at all potentialdistances from the emitter. Also preferably, the sensing target is thedominant reflective surface within the sensing area. Because theresolution of distance encoding systems depends on precisely judgingchanges in intensity of the reflected radiation, light leaks and othernoise sources can be especially problematic. Preferably, the portions ofthe sensing area, the area impinged upon by radiation from the sensor,that aren't the sensing target, are selected to absorb radiation.

Data Processing

Preferably, embodiments of the present invention process data from asensor to achieve resolutions higher than otherwise possible. A varietyof processing techniques, methods and elements are employed withinvarious embodiments of the invention.

Preferably, embodiments of the present invention encode detectedradiation into a voltage representative of current generated at thesensor. The signal voltage varies depending on the proportion ofradiation reflected by the sensing target at time of encoding.

In some embodiments the signal is a continuous encoding of the current,in other embodiments the signal is a series of discrete samples taken ata particular frequency. In either case, the signal preferably containsmultiple samples related to a critical time unit for which resolution isneeded. In other embodiments, the frequency is preferably selected totake a minimum number of samples per unit change in the current.

The encoding process produces a variable signal representing themovement of the sensing target. The minima and maxima of the signalrepresent extremes in the position of the sensing target.

A processing system receives a variable signal from the sensor andproduces corrected movement data. For example, in some embodiments, theanalog signal is supplied to an analog to digital converter (ADC). Theanalog signal, which was produced at a sampling rate that results inmultiple samples per critical time unit or per unit change in current,contains sufficient information to support ADC production of digitalsignal with a sufficient resolution. In some embodiments, an ADC processusing multiple thresholds is used to encode an analog signal to ahigher-resolution digital signal.

The corrected movement data is then translated into position data thatrepresents the position of a functional group coupled to the sensingtarget. For example, in some embodiments digital data from the ADC issupplied to a controller where it is analyzed and translated intoposition data.

Preferably, embodiments include additional calibration of processingcircuitry. In the preferred embodiment, an initial calibration isaccomplished automatically during power on. For example, in an ADC-basedsystem, self-calibration during power-on preferably determines the inputrange needed for data. In addition, the calibration preferably definesthe initial position for each functional group. In some embodiments,these initial positions are determined by a hard reference stopdiscussed elsewhere in greater detail. In some embodiments, thepositions are determined via information embedded into the sensingtarget. In addition, the overall distance between reference stops can beused to recalibrate the position sensors.

In some embodiments, non-volatile memory elements are included in thecontrol or processing circuitry and used to provide additionalmanufacturing and calibration data.

Preferably, this additional data is used to adjust for componentvariation and manufacturing tolerances.

Some embodiments that employ interpolation use additional hardwareand/or firmware (e.g. a clock for timing and for analysis). If theactuator is very nonlinear, interpolation can introduce positioningerror. Preferably, embodiments of the present invention use ADCtechniques.

Configurations

Embodiments of the present invention include position sensing systemsthat employ a variety of different configurations of sensors and sensingtargets. Some embodiments include direct distance sensing targetsconfigured to permit a position sensor to determine its distancetherefrom. In addition, some embodiments include linear sensing targetscoupled to a functional group and configured to move therewith. Thesensing systems discussed in the examples below are illustrated withlinear sensing targets; however, the methods, strategies and equipmentdescribed are also contemplated for use with distance targets withinsome embodiments of the present invention.

For example, a system employing a linear sensing target is illustratedin FIG. 15A. As shown by the cross sectional view, a position sensingsystem includes the linear target 3350 positioned a distance d from theemitter/detector 3030. The field of view of the emitter/detector 3030subtends a region of the target 3350 that includes a maximum of twotransitions. In some embodiments the emitter/detector is aphotoreflector. In some embodiments the emitter is an LED. In someembodiments the emitter/detector 3030 is a photoreflector.

The dark bands of the sensing target tend to absorb radiation emittedfrom the emitter, while the light bands of the sensing target tend toreflect radiation emitted from the emitter. The sensors detecttransitions in absorption and reflectance as the bands move relative tothe sensor windows.

In some embodiments, a detector encodes a given transition at differentpoints in time. In addition, in some embodiments, a detector includesmeans for encoding a transition in two data forms that differ by aconstant, such as a phase. In some embodiments two separate sensorsencode transitions out of phase of one another. In other embodiments, asingle sensor views transitions at two different points in space.Preferably, in these embodiments a control system combines theout-of-phase data, permitting it to detect a direction of movement aswell as its magnitude.

A position sensing system provides position data for a lens group overits range of motion. In some embodiments of the present invention, aposition sensing system tracks the relative position of an optics groupto within 70 microns over a range of 10 mm. In addition, processingsteps as outlined above are preferably employed to increase resolutionabove that offered natively by the target.

Operation

Preferred systems employ the position sensor data to control anactuator. In some embodiments, the data is used to predict the movementper cycle of the actuator. In some embodiments, the data is used topredict the movement per unit time that the actuator is engaged andpowered on. In some embodiments, the data are used on a real-time basiswith a correction cycle for increased accuracy. Preferably, theparticular implementation used is determined in accordance with theparticular actuator used.

Some embodiments of the present invention use the position data duringzoom and auto-focus operation to accurately position and track opticsgroups. Preferably, during zoom operation, multiple lens groups aremoved and tracked. The actuator control circuitry preferably accuratelyinterprets position data to accomplish tracking and movement. In someembodiments, the control circuitry uses tracking interpretation datathat is stored in a table. In some embodiments, the control circuitryuses tracking interpretation data that is stored as a mathematicalfunction. Sometimes, this data is defined in a calibration cycle.Preferably, this calibration cycle takes place during manufacturing.

In addition, the actuator control circuitry preferably accomplishes zoomoperations within a specified time frame. Preferably, in embodimentsthat relate to video optics, the zoom operations are accomplished in amanner that does not disturb video recording. In some embodiments, thezoom range and frame rate are used to determine an optimal step size.For example, the total zoom range is divided by the number of frameswithin the desired seek time to yield the step size. Thus, each step canoccur within a frame. Preferably, when zoom operations occur, the stepsare synchronized with the frame rate. In addition, the movement ofmultiple groups during zoom operations is preferably interleaved. Thus,as each group is moved, the remaining groups are stationary.Interleaving reduces driver and instantaneous power requirements.

In addition, during auto focus operation, typically a single group ismoved. Preferably, a group is moved through a focus range in smallincrements. Preferably, an accurate position sensor and actuator controlcircuit is employed to permit s positioning in increments below 20micrometers. In addition, though a variety of circuitry and hardware canbe used to implement the auto-focus algorithm, preferred implementationspermit reliable return of the group to the position that shows bestfocus.

As described above, the optical elements of some embodiments are dividedinto two groups, one group housed in a front barrel, the other grouphoused in a rear barrel. Typically, the precise motion of these opticsgroups group within confined spaces is achieved by using themechanism(s) described above.

The form factor of the auto-focus and zoom module of some embodiments isapproximately 9×14×22 mm without a prism or approximately 9×14×30 mmincluding a prism.

Method

FIG. 14 illustrates a general method consistent with some embodiments ofthe present invention. The method drives a functional group within asystem for positioning a functional element. The method comprises a step710 of coupling a first friction surface to a functional group. Anotherstep, 720 is coupling a second friction surface to the functional groupat one of an obtuse angle and a straight angel to the first frictionsurface. Yet another step, 730 is configuring a first drive element of avibrational actuator assembly to interact with the first frictionsurface. Another step 740 is configuring a second drive element of thevibrational actuator assembly to interact with the second frictionsurface. Still another step 750, is operating the first drive elementand the second drive element of the vibrational actuator assembly totranslate the optics housing.

While the invention has been described with reference to numerousspecific details, one of ordinary skill in the art will recognize thatthe invention can be embodied in other specific forms without departingfrom the spirit of the invention. Thus, one of ordinary skill in the artwill understand that the invention is not to be limited by the foregoingillustrative details, but rather is to be defined by the appendedclaims.

1. A system for positioning a functional element, comprising: a) ahousing; b) a primary guide pin coupled to the housing and registeredrelative to the housing; c) a functional group movably coupled with theprimary guide pin, comprising a functional element, a first frictionsurface, and a second friction surface, the first and second frictionsurfaces are oriented relative to one another at one of an obtuse angleand a straight angle; and d) a vibrational actuator assembly coupled tothe housing and substantially registered relative to the housing, andincluding a first drive element and a second drive element, wherein thefirst drive element is configured to interact with the first frictionsurface and the second drive element is configured to interact with thesecond friction surface, and the vibrational actuator assembly operatesto translate the functional group.
 2. The system for positioning afunctional element of claim 1, wherein the vibrational actuator assemblyfurther includes a first piezoelectric element coupled to the firstdrive element.
 3. The system for positioning a junctional element ofclaim 1, wherein the vibrational actuator assembly further includes asecond piezoelectric element coupled to the second drive element.
 4. Thesystem for positioning a functional element of claims 3, wherein thepiezoelectric elements are each in the form of a parallelepiped.
 5. Thesystem for positioning a functional element of claims 3, wherein thepiezoelectric elements are each configurable to operate at a resonantfrequency having at least two node points, and is constrained at twonode points.
 6. The system for positioning a functional element of claim1, wherein the vibrational actuator assembly further comprises a springconfigured to deform the resilient mounting structure to urge the firstdrive element against the first friction surface and the second driveelement against the second friction surface.
 7. The system forpositioning a functional element of claim 1, wherein the first driveelement and the second drive element are each in the form of a hollowcylinder.
 8. The system for positioning a functional element of claim 1,wherein a virtual line drawn between a point of the first frictionsurface, a point of the second friction surface, and a point of theguide pin is a straight line.
 9. The system for positioning a functionalelement of claim 1, wherein no virtual line drawn between any point ofthe first friction surface, the second friction surface, and the guidepin forms a straight line, but the virtual line does form a triangle.10. The system for positioning a functional element of claim 9, whereinthe triangle has a minimum area possible for a given spacing between thefirst friction surface and the second friction surface.
 11. The systemfor positioning a functional element of claim 1, wherein the frictionsurfaces are each arranged on a portion of a parallelepiped.
 12. Thesystem for positioning a functional element of claim 1, furthercomprising a position sensor configured to detect movement of thefunctional group.
 13. The system for positioning a functional element ofclaim 1, further comprising a control element, configured to receivedata from the position sensor and to operate the vibrational actuator toposition the functional element.
 14. The system for positioning afunctional element of claim 1, further comprising a mechanical stopelement coupled to the housing and configured to contact the functionalgroup at a first position and a second position and mechanically stopmovement of the functional group.
 15. The system for positioning afunctional element of claim 14, wherein the functional group includes anopening configured to interface with the mechanical stop element.
 16. Amethod of driving a functional group within a system for positioning afunctional element, comprising: a) coupling a first friction surface tothe functional group; b) coupling a second friction surface to thefunctional group at one of an obtuse angle and a straight angel to thefirst friction surface; c) configuring a first drive element of avibrational actuator assembly to interact with the first frictionsurface; d) configuring a second drive element of the vibrationalactuator assembly to interact with the second friction surface; and e)operating the first drive element and the second drive element of thevibrational actuator assembly to translate the optics housing.
 17. Anoptical module, comprising: a) a housing; b) a primary guide pin coupledto the housing and registered relative to the housing; c) an opticsgroup slidably coupled to the primary guide pin and including a firstfriction surface and a second friction surface, each arranged along anaxis parallel with the primary guide pin, the first friction surfacedirected along an axis perpendicular to the primary guide pin, and thesecond surface directed along the axis perpendicular to the primaryguide pin in a direction substantially opposite the first frictionsurface; d) an optics element rigidly coupled to the optics group; e) avibrational actuator assembly substantially registered relative to thehousing, and including a first drive element and a second drive element,wherein the first drive element is configured to interact with the firstfriction surface and the second drive element is configured to interactwith the second friction surface, and the vibrational actuator assemblyoperates to translate the optics group; and f) a sensing target coupledto the optics group and configured to permit detection of translation ofthe optics group; g) an image sensor coupled to the housing andregistered relative to the housing.
 18. The optical module of claim 17,wherein the vibrational actuator assembly further includes a firstpiezoelectric element coupled to the first drive element.
 19. Theoptical module of claim 17, wherein the vibrational actuator assemblyfurther includes a second piezoelectric element coupled to the seconddrive element.
 20. The optical module of claims 19, wherein thepiezoelectric elements are each in the form of a parallelepiped.
 21. Theoptical module of claims 19, wherein the piezoelectric elements each areconfigurable to operate at a resonant frequency having at least two nodepoints, and is constrained at two node points.
 22. The optical module ofclaim 17, wherein the vibrational actuator assembly further comprises aspring configured to deform the resilient mounting structure to urge thefirst drive element against the first friction surface and the seconddrive element against the second friction surface.
 23. The opticalmodule of claim 17, wherein the first drive element and the second driveelement are each in the form of a hollow cylinder.
 24. The opticalmodule of claim 17, wherein a virtual line drawn between a point of thefirst friction surface, a point of the second friction surface, and apoint of the guide pin is a straight line.
 25. The optical module ofclaim 17, wherein no virtual line drawn between any point of the firstfriction surface, the second friction surface, and the guide pin forms astraight line, but the virtual line does form a triangle.
 26. Theoptical module of claim 22, wherein the triangle has a minimum areapossible for a given spacing between the first friction surface and thesecond friction surface.
 27. The optical module of claim 17, wherein thefriction surfaces are each arranged on a portion of a parallelepiped.28. The optical module of claim 17, further comprising a position sensorconfigured to detect movement of the optical group.
 29. The opticalmodule of claim 17, further comprising a control element, configured toreceive data from the position sensor and to operate the vibrationalactuator to position the optical element.
 30. The optical module ofclaim 17, further comprising a housing coupled to the primary guide pinand to the vibrational actuator assembly.
 31. The optical module ofclaim 30, further comprising a mechanical stop element coupled to thehousing and configured to contact the optical group at a first positionand a second position and mechanically stop movement of the opticalgroup.
 32. The optical module of claim 31, wherein the optical groupincludes an opening configured to interface with the mechanical stopelement.
 33. The optics module of claim 17, further comprising asecondary guide pin coupled with the optics group.
 34. The optics moduleof claim 17, further comprising a secondary optics group coupled withthe primary guide pin and including a secondary first friction surfaceand a secondary second friction surface, each arranged along an axisparallel with the primary guide pin, the secondary first frictionsurface directed along an axis perpendicular to the primary guide pin,and the secondary second surface directed along the axis perpendicularto the primary guide pin in a direction substantially opposite thesecondary first friction surface.
 35. The optics module of claim 34,wherein the secondary optics group further comprises a secondary opticselement.
 36. The optics module of claim 34, further comprising asecondary vibrational actuator assembly including a secondary firstdrive element and a secondary second drive element, wherein thesecondary first drive element is configured to interact with thesecondary first friction surface and the secondary second drive elementis configured to interact with the secondary second friction surface,and the secondary vibrational actuator assembly operates to translatethe secondary optics group.
 37. The optics module of claim 36, whereinthe optics element and the secondary optics element are aligned todeliver an image to the image sensor.
 38. The optical module of claim36, further comprising a control element configured to receive data froma secondary position sensor and to operate the secondary vibrationalactuator to position the secondary optical element.